Attention-deficit hyperactivity disorder (ADHD) is a potentially serious and often underdiagnosed condition in adulthood. ADHD adults often have other psychiatric disorder such as high rates of substance use disorders, antisocial personality disorder, and mood and anxiety disorders. These data suggest that rates of ADHD would be high in opioid abusers, especially in light of the high rates of antisocial and mood disorders reported in this group. The prognostic significance of psychiatric comorbidity in drug abusers has been extensively studied for several specific disorders (e.g., mood, anxiety and antisocial personality), yielding major findings. Despite this, only one study has been conducted of hyperactivity symptoms in opioid abusers. The present project extends that work. The specific aims of this study are to l) determine the frequency of ADHD using operationalized diagnostic criteria in a large series of opioid abusers; 2) determine the proportion of patients with the childhood ADHD diagnosis who have adult symptoms and assess the pattern and severity of impairment; 3) examine the patterns of drug use and other psychiatric disorder in opioid abusers with and without the ADHD syndrome; 4) determine the relationship between ADHD and treatment outcome using objective and self-report indices of drug use and treatment survival. The proposed study will draw on the usual care practices and resources of an established methadone maintenance (MM) program with an ongoing research program. This includes counseling, urine testing, and an extensive psychiatric and substance abuse assessment battery (including Structured Clinical Interview for DSM-III-R: SCID; and Addiction Severity Index: ASI). Study participants (N=l79) will be recruited from a convenience sample of opioid abusers entering MM treatment during the grant year. Best estimate rates of ADHD in opioid abusers indicate that approximately 25% will meet lifetime criteria for the disorder. After obtaining informed consent, patients will be paid to complete the Diagnostic Schedule for DSM-IV (DIS 4.0) to diagnose childhood and adult ADHD, and pattern and severity of symptoms will be rated. Consent will be obtained to speak with subjects' parents about childhood ADHD symptoms in order to improve assessment of ADHD. The Continuous Performance Test (CPT) will be administered as an objective measure of attention. The CPT has been shown to discriminate between hyperactive patients and normal controls. Evaluations and testing will be conducted by the principal investigator, a board certified psychiatrist. Urine screens, drug use self reports, and retention data will be used to assess the relation between ADHD and treatment outcome. The study will determine the frequency of ADHD using DSM-IV criteria and a structured interview in opioid drug abusers entering MM treatment. Equally important, new information will be obtained about the extent, pattern, and severity of adult ADHD impairment in this population. The relations between ADHD and patterns of substance use and other psychiatric disorders will be examined, and the impact of ADHD on two critical indices of treatment outcome will be evaluated.